The present invention relates to the field of audio processing and, more particularly, to the field of audio data shuffling in a digital video environment.
The Digital Video (DV) format is quickly becoming the standard for many digital video applications, including consumer electronic video devices. For example, DV format camcorders can now be found with more frequency and at more competitive prices than the conventional analog 8 mm and VHS camcorders. At the same time, DV camcorders provide advantages which are inherent to digital technology, such as high quality of video and sound, digital filtering, digital error correction, and the like. DV provides quality at or higher than the high-end of the conventional analog camcorders such as Hi-8 mm and S-VHS, with much added flexibility. Also, digital format data can be repeatedly copied without loss of quality.
Applications involving digital video applications often involve digital audio data as well. In a typical prior art technique, the analog audio data is provided to an analog-to-digital converter. The analog-to-digital converter converts the analog audio data into digital audio data. The digital audio data may then be provided in the form of a bitstream to an audio processor. The audio processor shuffles the digital audio data in the bitstream. The shuffling of the audio digital data allows for more efficient storage of the digital audio data in a memory.
The Blue Book discusses two modes: a National Television System Committee (NTSC) standard and a Phase Alternation System (PAL) standard. Among other differences, the NTSC standard and the PAL standard require different techniques to shuffle digital audio data. To shuffle digital audio data, a track number, a block number, and a data position number are calculated to specify the location of a particular sample of a pair of digital audio data in a frame. For the NTSC standard, three separate calculations are required to determine the track number, block number, and a data position number for a sample. Likewise, for the PAL standard, another three distinct calculations are required to determine the track number, block number, and a data position number for a sample. The determination of the track number, the block number, and the data position for either standard requires relatively complex calculations involving a value n, where n designates the nth pair of digital audio data in the bitstream.
The implementation of conventional audio shuffling equations for both the NTSC standard and the PAL standard present significant disadvantages. For example, because conventional audio shuffling equations for the NTSC standard are different from those for the PAL standard, separate hardware is necessary to perform calculations associated with each system. As another example, performing the calculations for the track number, block number, and data position number requires the use of a multiplier and a divider. Such use is costly in terms of the dedicated space required on an integrated circuit to accommodate the multiplier and divider.
An innovative technique is necessary to overcome these and other disadvantages associated with the conventional shuffling of digital audio data. The innovation should provide a simple, efficient solution that may apply substantially equally for both the NTSC standard and the PAL standard in determining track number, block number, and data position number information. Such a solution would provide hardware savings and more versatility to digital audio data shuffling applications. Furthermore, the innovation should allow the calculation of a track number, block number, and a data position number in a manner that minimizes or eliminates the burdensome need for involved calculations. Such reduction or elimination would advantageously decrease the space on an integrated circuit dedicated to perform the involved calculations. In addition, to maximize economy and efficiency in applications involving both digital video data digital audio data, the innovation should allow the storage of shuffled digital audio data in unused portions of a memory that also stores digital video data.
The present invention solves the problems associated with the prior art by providing methods and apparatus for providing audio in a digital video system.
In accordance with one aspect of the present invention, a method and apparatus is provided for storing digital audio data in a memory. The memory has digital video data stored in a first portion of the memory. A set of values is calculated. The digital audio data is shuffled according to the set of values. The digital audio data is stored in a second portion of the memory, the second portion not identical to the first portion.
In another aspect of the present invention, a value n is determined. The set of values is determined based on the value of n.
In yet another aspect of the present invention, digital audio data is stored in a memory location based on the set of values.